Earth-sized planet found in star’s habitable zone

Exoplanet could have liquid water, which astronomers consider crucial for possible alien life

A LOT LIKE HOME An Earth-sized planet capable of hosting liquid water and four other worlds orbit the cool red star Kepler-186, as seen in an artist’s illustration. The planet, found in data from the Kepler space telescope, is the smallest planet found in a star’s habitable zone.

NASA Ames, SETI Institute, JPL-Caltech

Earth, meet your distant cousin. The Kepler space telescope has turned up a potentially water-bearing world nearly as small as our planet. The planet is the smallest one found in any star’s habitable zone, a temperate region surrounding a star that is suitable for liquid water.

Elisa Quintana, an astronomer at the NASA Ames Research Center in Moffett Field, Calif., and colleagues discovered the planet, Kepler-186f, in data from the first three years of Kepler’s mission. The planet is 10 percent larger than Earth and orbits a type of star called an M dwarf, a red star that is smaller, cooler and fainter than the sun. The planet circles the star Kepler-186 once every 130 days in an orbit slightly smaller than Mercury’s. The star, which is 490 light-years away in the Cygnus constellation, also hosts four other roughly Earth-sized planets. Previously discovered by Kepler, the other planets are much closer to the star, whipping around in as little as 3.9 days.

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